Update test_build_linkcheck.py

Author: FazeelUsmani

tests/test_builders/test_build_linkcheck.py

@@ -1564,3 +1564,32 @@ def mock_request(self, method, url, **kwargs):
     if lowercase_uri in rowsby:
         # Should be working because case is ignored
         assert rowsby[lowercase_uri]['status'] == 'working'
+
+@pytest.mark.sphinx(
+    'linkcheck',
+    testroot='linkcheck-localserver-anchor',
+    freshenv=True,
+    confoverrides={'linkcheck_ignore_case': True},
+)
+
+def test_linkcheck_anchors_remain_case_sensitive(app: SphinxTestApp) -> None:
+    """Test that anchors remain case-sensitive even with linkcheck_ignore_case=True."""
+    with serve_application(app, CaseSensitiveHandler) as address:
+        # Create a document with an anchor in lowercase that doesn't match HTML
+        index = app.srcdir / 'index.rst'
+        index.write_text(
+            f'* `Link with wrong case anchor <http://{address}/anchor.html#myanchor>`_\n',
+            encoding='utf-8',
+        )
+        app.build()
+
+    content = (app.outdir / 'output.json').read_text(encoding='utf8')
+    rows = [json.loads(x) for x in content.splitlines()]
+    
+    # The HTML has "MyAnchor" but we request "myanchor"
+    # Even with linkcheck_ignore_case=True, anchors should be case-sensitive
+    # so this should be broken
+    assert len(rows) == 1
+    assert rows[0]['status'] == 'broken'
+    assert rows[0]['uri'] == f'http://{address}/anchor.html#myanchor'
+    assert "Anchor 'myanchor' not found" in rows[0]['info']